Question

whats the square root of 10

Answer 1

The square root of 10 is an irrational number, so there's no other way to express it, if not saying that it is a number that gives 10 when squared.

You write it as $\sqrt{10}$, and as all square roots, its property is that

$\sqrt{10}^2 = 10$

If you want its decimale expansion, you can only approximate it, using as many digits as you like, but you can never write all the digits of the decimal part, because they are infinitely many and with no pattern:

$\sqrt{10}\approx 3.16227766017\ldots$